K.Mandla's blog of Linux experiences

Circumventing a lack of USB CD support

I don’t go looking for problems, I swear. It’s not in my character. All these little puzzles and conundrums that I document usually happen to me without active efforts to search them out. Trust me: The last things I need to do is to go looking for more problems to solve.

This time though, the issue is fairly easy to identify but requires a few steps to get around. It seems that the Crux 2.6 installation CD doesn’t carry support for USB CDROMs in its spinup sequence — which means the disc will boot, but it’s unable to reach the login prompt because it can’t find the source drive. I’m guessing the kernel lacks whatever module is necessary to find it, but of course I am probably wrong.

In this particular situation I was rebuilding the system for my Pentium. Since the X60s uses SATA drives instead of the old IDE connection, I have to use an external enclosure to connect to the machine anyway. However, just chrooting into the external drive causes Grub some confusion when I try to install it, so I went with another approach.

I installed a very very basic version of Crux within Qemu, booting from the ISO file and setting the disk image file size to something similar to the size of the target drive. In retrospect there was no need for that; just setting it to something smaller would save time later, and avoid discrepancies between the actual size of the drive and the size of the image. You know, that whole 40-gigabyte-but-not-really-because-companies-count-differently-from-normal-humans thing.🙄

The problem with Qemu is that virtual systems (in my meager experience) don’t run at full speed, and I want this machine to compile without the need to manage X, the desktop, etc. So I passed the compiled kernel from the old system across the Internet to the virtual system, then installed Grub to get that chore out of the way.

From there I used dd to send the image to the actual drive, which even on USB2.0 was rather time-consuming. When it was done though, I could chroot into the system in the same manner as is suggested in the Crux handbook. With Grub no longer an obstacle, I could build a fresh kernel and continue installing at full speed.

And lucky me, when it was all said and done, it booted fine and worked just as well as the standing installation.

I suppose I should mention that all of this was done from within Arch, although that might have no bearing on the final results.

My plan at this point is to use a similar trick when I install Crux on the X60s itself, which was my original goal. I may take a shot at transferring the Crux ISO to a USB flash drive and seeing if that will boot through, but to be honest, I have my doubts. I’ll check on #crux to see if that behavior is planned in the first place, or to see if there should be a bug report somewhere. I don’t know anyone with a netbook that uses Crux, but it seems that computers like that would also need to be able to boot from a USB CDROM to install.

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5 thoughts on “Circumventing a lack of USB CD support”

just a few days ago my eeepc’s hard drive started dying and spitting errors. badblocks were just mating and multiplying with every new run.
but thanks to your blog i tried badblocks -w and restored previously rsync’d -a whole system, and it’s working now! anyway these drives are not long livers.